This research project aims to improve current understanding of motivational and species-typical behaviors, including aggression and thermoregulation, by localizing and analyzing the functions of their brain mechanisms, and investigating the specific sensory inputs that control their performance and produce associated reward effects. Studies of sensory reward will include detailed analyses of the reinforcing properties of 1) localized stimuli associated with biting attack elicited by hypothalamic stimulation in cats and 2) localized central and peripheral thermal stimuli in thermoregulation in rats. The differentiated functions of different central and peripheral thermoreceptors in control of thermoregulatory behaviors will be studied in rats using brain lesions, localized thermal stimulation, and summation methods with the aim of clarifying the functional and anatomical organization of the system and its functioning under different types of natural heat stress.